underweightlow weight-for-age, reflecting a current
condition resulting from either inadequate food
intake, past episodes of undernutrition or poor
health conditions

vulnerability
presence of factors that place people at risk of
becoming food insecure or malnourished

wasting low
weight-for-height, generally the result of weight
loss associated with a recent period of starvation
or severe disease

A note
on methodology - how the numbers are calculated

Chronic food insecurity is represented by estimates of
the number of people whose food intake does not provide
enough calories to meet their basic energy requirements -
i.e. the undernourished. Measurements of nutritional status
or undernutrition, on the other hand, are based on
information about people's actual physiological
condition.

In practice, these are two distinct and useful measures
derived from very different analytical approaches.

1. Undernourishment is estimated from existing
data about numbers of people and the amount of food
available to them.

2. Undernutrition is determined from data about
people's weight, height and age. Ratios calculated from
these measurements indicate the outcome not only of
inadequate food intake but also of poor health and
sanitation conditions that may prevent people from deriving
full nutritional benefit from what they eat.

The two approaches are complementary, as illustrated:

The numbers cited in this section refer to estimates of
undernourishment based on a few commonly available types of
information:

food production, trade and stocks;

figures for total population and distribution by age
and gender; and

data on consumption distribution.

The method is described in detail in The Sixth World Food
Survey, published by FAO in 1996. Very briefly it relies
on:

1. calculating the total number of calories available
from local food production, trade and stocks;

2. calculating an average minimum calories requirement
for the total population based on the number of calories
needed by different age and gender groups and the proportion
of the population each group represents;

3. dividing the total number of calories available by the
number of people in the country;

4. factoring in a coefficient for distribution to take
account of inequality in access to food;

5. combining this information to construct the
distribution of the food supply within the country. This
gives the percentage of the population whose food intake
falls below the minimum requirement;

6. multiplying this percentage by the size of the
population to obtain the number of undernourished
people.

These calculations produce an estimate of the number of
people in each country whose average calorie intake falls
below the minimum required to keep the body going and
perform light activity. Adding these numbers together yields
a global estimate of the total number of undernourished
people.

Measuring nutritional
status

Measurements of undernourishment are based on estimates
of food intake. But to measure malnutrition it is necessary
to use anthropometric indicators that tell what is happening
to people's bodies.

Estimates of food intake and anthropometry have different
objectives, and each has advantages and limitations.
Anthropometric data are currently used primarily to measure
the nutritional status of young children. Three different
measures of undernutrition are commonly used: wasting,
stunting and underweight. Nutritionally deprived children
are those who are significantly smaller compared to commonly
used uniform standards for child growth.

By contrast, in this report prevalence of
undernourishment is measured for a total population by
comparing food intake data with country-specific food need
standards. These are determined on the basis of energy
requirements of each sex-age group, taking into account sex-
age specific heights within the population.

Anthropometric data are obtained through surveys whose
frequency and timing vary from country to country. As a
result, these data must be used cautiously in making
comparisons between countries and time periods. Food intake
measurements, on the other hand, rely on data that are more
readily available, recent and fully comparable across
countries. So they can be used effectively to obtain a
snapshot of current conditions, even though they do not
capture the full array of factors determining nutritional
status.